1. Field of the Invention
The present invention relates to a technology for transmitting pulse signals, such as a power-on signal and the like.
2. Description of the Related Art
Recently, personal computers (hereinafter called “PC”) provided with a television (hereinafter called “TV”) function, have become widely spread. In such a PC, TV broadcast can be received independently of its PC function. A PC provided with a remote-control transmitter for transmitting a variety of instructions including power-on is also known of.
When switching the power of a PC on, a user presses a power button provided for the remote-control transmitter. In this case, a remote-control transmitter comprises a PC power button for activating a PC function and a TV power button for activating a TV function. Radio signals transmitted from the remote-control transmitter are received by a remote-control receiver. When detecting a signal from the remote-control transmitter, the remote-control receiver generates a PC-on signal for activating the PC function or a TV-on signal for activating the TV function. Then, the generated signal is transmitted to the PC main body via a signal line to activate the PC function or TV function.
FIGS. 1A and 1B show examples of the configuration of a conventional PC. FIG. 1A is an example of the configuration of a PC without a TV function. FIG. 1B is an example of the configuration of a PC with a TV function.
In a conventional PC with a TV function, a signal line for transmitting a TV-on signal from the remote-control receiver to the PC main body is provided separately from a signal line for transmitting a PC-on signal. Therefore, the same cable and connector cannot be commonly used for both a PC with a TV function and a PC without a TV function.
As to prior art for transmitting signals other than a PC power-on signal, Japanese Patent Applications No. H7-288768 (U.S. Pat. No. 5,784,499) and S55-4110 disclose a technology for transmitting a plurality of signals using the same signal line and a technology for separating signals transmitted via the same signal line.